Automatic stop device for motionpicture projectors



Dec. 11, 1951 v P. s. NIELSEN 2,577,909

AUTOMATIC STOP DEVICE FOR MOTION-PICTURE PROJECTORS Filed May 25, 1949INVENTOR ATTORNEYS Patented Dec. 11, 1951 UNITED STATES PATENT OFFICEAUTOMATIS STOP DEVICE FOR MOTION- PICTURE PROJECTORS 1 Claim.

This invention relates to an automatic stop device for motion pictureprojectors.

It is an important object of the invention to provide a means forautomatically stopping the motor of a projector when a film break occurswhich will be simple, sure, and swift in its operation.

Another important object of the invention is to provide a device of thetype stated which can be installed in a conventional motion pictureprojector without necessity of modification of the projectorconstruction, and without affecting in any way the normal operation ofthe projector or the normal arrangement of the components parts of theprojector.

Another important object is to provide a device of the type stated whichwill be constructed with a minimum of parts simply arranged, will occupya minimum of space, and will be capable of being sold and installed atlow cost.

With the foregoing and other objects in view which will appear as thedescription proceeds,

the invention consists of certain novel details of construction andcombinations of parts, hereinafter more fully described and pointed outin the claim, it being understood that changes may be made in theconstruction and arrangement of parts without departing from the spiritof the invention as claimed.

Referring to the drawings Fig. i is a sectional view through a portionof a projector showing, in side elevation, the automatic stop device ofthe invention.

Fig. 2 is a perspective view, portions being broken away, of the mainportion of said device.

Referring to the drawings in detail my automatic stop device ismountable in a conventional motion picture projector including a frontwall 5, bottom plate 6, rear wall 1, main drive shaft 8, and lowertake-up sprocket 9 over which is threaded the film Ill.

The invention includes a stationary supporting bracket I! readilystamped from a suitably shaped metal blank and formed at one end withthe upturned transverse flange l2 adapted to be positioned against theinner surface of the front wall 5 as clearly shown in Fig. l, and formedwith the spaced openings l3 through which extend the fastening means idfor securing said bracket firmly and immovably to the front wall.

The intermediate portion of the bracket 1 I can be supported uponunderlying portions of the bottom plate 6. and the other end of thebracket II is extended to partially overlie the usual bottom openingformed in the plate 6, through which the film In passes, said other endof the bracket l i being formed with the hinged portion [5 adapted to bealigned with hinged portions l6 formed on one end of the swinging arm I!also capable of being readily stamped to shape from a suitable metalblank. Hinge pin I 8 extends through the aligned cooperating hingedportions 15, it for the purpose of swingably mounting the arm ll uponthe stationary bracket II. Intermediate its ends the arm I1 isintegrally formed with the spaced spring wings l8 having at their freeends the inwardly extended clamping portions H3. The portion of the armit that is disposed between the wings I8' is outstruck to provide aninclined tongue 20 which is bent to a desired angle of inclinationrelative to the arm H. as shown particularly in Fig. 1. As seen from thedrawings, the clamping edge portions, being pressed inwardly, overhangthe side edges of the tongue 29 in any selected position of angularityto which the tongue is adjusted relative to the arm ll, so as to grip amercury switch, to be described hereinafter, to hold it against thetongue in longitudinal contact with the tongue, thereby causing themercury switch to assume the same position of angularity relative to thearm ll as is assumed by the tongue. In each selected position ofadjustment of the tongue, the spring wings [3' are proportioned andlocated to constitute side walls that hold the mercury switch againstlateral shifting off the tongue, in any adjusted position of the tongue.

The free end of the arm IT is transversely curved at 2i to provide acontact surface with the film it that will reduce frictional contactbetween the arm ii and the film It to a minimum.

As may be noted, both the supporting bracket l and the swinging arm Hcan be formed from single blanks of sheet metal capable of being diestamped in quantity to the desired shapes.

A mercury switch 22 is pressed against the tongue 20 and is disposedbetween and clamped by the spring wings l8 and clamping portions Id, sothat said mercury switch 22 is secured to the arm i! at the same angleof inclination as the tongue 20.

Extending from the mercury switch 22 are the leads 23, 24 which arepreferably secured to the bracket 1 i as by a hold-down clamp 25, andsaid leads are then extended through a suitable opening formed in thefront wall 5. One of the leads can have, exteriorly 0f the projector,the manually operated main switch 26, while the other lead extends tothe motor 27, said switch and motor being in circuit with each other andwith the switch 22 and extending to the ordinary house supply 28. Ibelieve the use of the automatic stop device will be readily apparent.Assuming that the device has been mounted as shown and described, thearm I T is elevated to the full line position illustrated, in whichposition it is supported at a slight angle of inclination from thevertical, being held in said slightly inclined position by the film Itas the film runs through the projector in normal operation of theprojector.

Should a film break occur, the arm I! will immediately drop to thedotted line position illustrated in Fig. 1, and this will automaticallyposition the mercury switch 22 to break the circuit to the motor 21,thus to stop projector operation immediately and before the film canpile up or cause a film fire.

What is claimed is:

In an automatic stop device for motion picture projectors, a supportingbracket of onepiece construction formed from a length of wide fiatmaterial, one end of said bracket being adapted for fixed connection toa motion picture projector with the remaining portion of the bracketextending laterally and horizontally interiorly of the projector and inthe plane of film running through the projector, the other end of saidbracket being integrally formed with a horizontally disposed hingeportion; a swinging arm integrally formed from a single piece of flatmaterial of the approximate width of and in the plane of the film and ofsaid supporting bracket, said arm being integrally formed at one endwith a hinge portion cooperating with the hinge portion of thesupporting bracket and hingedly connected to the first-named hingeportion for vertical swinging of said swinging arm, said swinging armbeing formed at its other end with a curved film-contacting portion forsupporting of the swinging arm in a substantially upright po- 40 sitionwhen film is running through the projector, said film normallymaintaining said swinging arm against gravitational downward swing- 7pressed outwardly out of the plane of the swinging arm proper, thetongue being connected to the swinging arm at one end only of of thetongue and being bendable to selected positions of angularity relativeto the arm; andamercuryswitch clamped between said edge portions of thespring wings and held by said edge portions in longitudinal contact withsaid tongue, whereby to assume the same position of angularity to thearm as is assumed by the tongue, the edge portions being proportioned toextend outwardly from the arm a substantial distance beyond the tongueto overhang and be spaced above the side edges of the tongue in eachselected position of bendable ad justment of the tongue, said springwings constituting side walls located at opposite sides of the switchwhen the switch is clamped between the tongue and edge portions, toretain the switch against lateral shifting off the adjustably positionedtongue.

PETER S. NIELSEN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS TOdd Nov. 18, 194'?

